1. Field of the Invention
The present invention relates to a novel esterase which is useful as a catalyst for the hydrolyses of esters, methods for the isolation of said esterase, methods for the kinetic resolution of a mixture of a (R)- form and a (S)-form of an ester compound using said esterase, and methods using said esterase for producing optically active chroman-3-acetic acids and esters thereof, which are useful as medicinal materials.
Furthermore, the present invention relates to methods for producing optically active chroman-3-acetic acids and esters thereof, wherein a mixture of (3R)- and (3S)-chroman-3-acetic acid esters represented by the general formula (I) described below is treated with an ester hydrolase which has an optically selective hydrolyzing activity or microorganisms which carry said hydrolase, or a preparation therefrom.
2. Description of the Related Art
A number of attempts have been made in recent years to apply enzymes in organic syntheses. In particular, the use of esterases, which have high substrate specificities for the optically selective hydrolysis of various ester compounds selectively to thereby obtain optically active compounds, or for producing chiral compounds from prochiral ester compounds, has high industrial efficacy.
An esterase derived from porcine liver is generally used in such purposes as mentioned above but its high cost and limited availability precludes its industrial usage. The use of esterases from microbial sources in place of the esterase derived from porcine liver has been tried. Since enzymes derived from different organisms are characteristically different in their substrate specificities, the selectivity and reaction rate of the enzymes markedly vary depending on the compounds to which the enzymes are applied.
A 6-aminochroman-3-acetic acid ester disclosed in European Patent Publications, EP 0709370 and EP 0760364, is a useful intermediate of an antiplatelet. However, no esterase which shows high optical selectivity for 6-aminochroman-3-acetic acid esters and which can effectively hydrolyze them has been reported.
An objective of the present invention is to find an esterase which is optically selective and useful as a catalyst for producing optically active chroman-3-acetic acids and esters thereof, which are useful as medicinal materials.
Another objective of the present invention is to provide methods for the simple and efficient production of optically active chroman-3-acetic acids and esters thereof.